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GS 2 344 662 .
I
J
I
Page JL of S3
"UK Patent Application „„GB ,,,,2 344 662 ™ A
<43) Date of A Publication 14.06.2000
(21)
Application No 0005104.5
(0 1/
hut r*t 7
IIMT CL
(221
Data 0 f CW inn 7A 01 1QQ7
(52)
UK CI (Edition R )
Date Lodged 02.03.2000
G2J jwr
(30)
Priority Data
(56)
Documents Cited
(31) 03012317 (32) 26.01.1996 (33) JP
GB 2237406 A US 4707083 A
(31) 08034122 (32) 21.02.1996
(31) 08034132 (32) 21.02.1996
(58)
Field of Search . .
(31) 9614331 (32) 08.07.1996 (33) GB
UK CL (Edition R j G2J J23C
(62)
INTCL 7 G02B
Divided from Application No 9701431.0 under Section
15(4) of the Patents Act 1977
(72)
Inventor(s)
(71)
Hiroshi Nomura
Applicants)
Kazuyoshi Azegami
Asaihi Kogaku Kogyo Kabushikt Kaisha
Takamitsu Sasaki
(incorporated in Japan)
36-9 Maenocho 2-chome, ttabashi-ku, Tokyo, Japan
(74)
Agent and/or Address for Service
Ablett & Stabbing
Caparo House, 101-103 Baker Street LONDON,
W1M 1FD, United Kingdom
(54) Abstract Title
Lens cam mechanism with tapered slot and follower and stopper
(57) A cam mechanism used for a photographic lens has a movable barrel (19) arid a cam ring (17) fitted on
the movable barrel such that the moving barrel is movable relative to the cam ring along an optical axis of the
photographic lens. The cam mechanism includes: at least one tapered cam slot (17b) formed on the cam ring
which extends obliquely to a direction of the optical axis; at least one tapered follower projection (19a)
integrally formed on the movable barrel; at least one lead groove <17p) formed on an inner periphery of the
cam ring which allows for insertion of the follower projection into the at least one cam slot during an assembly
of the photographic lens; at least one follower (18a) respectively formed on the at least one follower
projection; and at least one stopper (17m) for contacting the at least one follower (18a) when the movable
barrel is fully retracted into the cam ring for preventing the movable barrel from coming out of the cam ring
the at least one stopper (17m) is integrally formed on an outer periphery of the cam ring (17).
Fig. 4
17bs
a
CD
ro
CO
*
>
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2/22
Fig. 2
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Fig. 6
)7
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Fig. 7
22e
GG 2 344 662
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Pag?. 11 o?. 83
10/22
Fig. 10
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Fig. 19
64
Object Distance
Measuring
Apparatus
65-
Photo metering
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Fig. 22
72 a
2344662
TELESCOPING TYPE OF ZOOM LENS AND CAM: MECHANISM
The present invention relates to a telescoping type of
zoom lens having a plurality of moving . barrels
concentrically arranged which advance from or retract into a
stationary barrel of the zoom- lens, and also relates to a
cam mechanism, which can be used in such a telescoping type
of zoom lens, for producing a Predetermined.. movement between
two moving barrels concentrically arranged.
. A telescoping: type of zoom lens having a plurality of
moving barrels concentrically arranged is well known'. This
•type of zoom lens is widely utilized in a lens-shutter type
. of zoom compact camera in order to reduce the thickness of
the camera when not in use.
in such a zoom , lens , in order to realize a moving
barrel (first barrel) to be movable forward or rearward
along an optical axis of the zoom lens relative to a second
barrel (which may be a stationary barrel or a moving barrel),
in which the moving barrel is positioned, male and female
helicoids (helicoid thread^ aT - 0
cnreaas) are often rormed on an outer
periphery of: the moving barrel- and an s^^-'- : ' ■ ■
y aj-xej. ana an inner periphery of . the
second barrel, respectively ' tk 0 ™~ • •
ycv.tive.iy. The moving barrel is
pa 2.344 662 _ ^ _ A _____ JPage 25_of 83
. 2
positioned in the second barrel with the male helicoid
engaging with the female helicoid. Due to the engagement of
the helicoids, the moving barrel moves along the optical
axis while rotating about the optical axis relative to the
second barrel when the moving barrel is driven to rotate
about the optical axis, instead of using such helicoids, in
order to realize the moving barrel to move forward or
rearward along the optical axis relative to the second
barrel, it is also often the case that a plurality of cam
slots or grooves, which are parallel to one another and
oblique to the optical axis direction, are formed on ' the
second barrel, and that a corresponding plurality of
follower pins are fixed on the moving barrel. In this case,
the moving barrel is positioned in the second barrel with
the follower pins respectively engaging with the cam slots
or grooves, so that the moving barrel can move along the
optical axis while rotating about the optical axis relative
to the second barrel .
In such a zoom lens, if a strong impact is applied to
the front end of the zoom lens in a direction of retraction
thereof while the moving barrel is advanced from the second
barrel, the moving barrel is forced to retract back into the
second barrel while rotating. For this reason, in order to
protect a gear train, provided in a drive mechanism for
moving the moving barrel, from being damaged, a clutch is
!
3
generally provided in the gear train. However, if a strong
. impact is applied to the front end of the zoom lens in a
direction of retraction thereof while the moving barrel is
fully retracted in the second barrel, the moving barrel is
forced to rotate in a rotational direction to further
retract into the second barrel. This results in damage to
the. moving barrel, the second barrel and/ or other peripheral
members, particularly in the case where the lead of the
helicoids or the lead of the cam slots or grooves is large,
i.e., where the helicoids or the caa slots or grooves are
formed such that the moving barrel moves by a large distance
along the optical axis for an amount of rotation of the
moving barrel relative to- the second barrel.
It is well known to provide a zoom lens in which a
moving barrel ,f irst barrel) u ' guUmA ^ ^ ^
without rotating thereabout relative to another barrel
(second barrel). The zoom lens is driven to move along the
optical axis by a cam mechanism including a cam ring
arranged concentric to the first barrel. The cam ring is
provided with a pluralitv nf , .
fj.uraj.icy of cam slots in which . a
corresponding plurality of followers -are respectively
fitted, so that the first ■ barrel- .moves'aloSg the -optical
axis 0 relative to the second barrel when the cam ririg
rotates about the optical axis relative to the first- barrel .
in such a conventional zoom lens, the cam slots are formed
GQ2.344862.
Page 27 of 83
• 4
on the cam ring such that side surfaces of each cam. slot,
which determine a predetermined contoured cam surface
thereof, extend parallel to each other and substantially
perpendicular to a part of the wall of the ■ cam ring where
•the cam slot is formed. However, when a cam ring provided
with a plurality of cam slots each having such a shape is
produced by molding, it is necessary to use a mold having a
complicated structure consisting of a plurality of
complicated mold pieces.
An object of the present invention is to provide a
telescoping type of zoom lens having a plurality of moving
barrels concentrically arranged, - which is provided with a
mechanism for preventing the zoom lens from being damaged *
when a strong impact is applied to the front end of the zoom
lens in a direction of retraction- thereof while the zoom
lens is fully retracted.
Another object of the present invention is to provide a
cam mechanism including a cam ring provided with a plurality
of cam slots' for producing a predetermined movement between
two moving barrels concentrically, arranged, which can be
used in a . telescoping type of zoom lens- and .which does not
require that the cam ring' be molded. "by a mold of- complicated
structure.
According
to an . aspect of . the. present invention, there is provided; a.
lens' . barrel;' having first,, second and " third' barrels
concentrically arranged in this order, from an optical axis.
The lens barrel includes: at least one cam slot formed on
the second barrel and extending oblique to a direction of
the optical axis; at least one guide groove formed on ■ an
inner periphery of the third barrel; at . least one follower
formed on an outer periphery of the first barrel and
engaging with the at least one guide groove through the at ■
least one cam slot; and at least one member integrally
formed on an outer periphery of the second barrel adjacent
to an end of the at. least one cam slot, .the at least one
member including a surface formed thereon to contact the at
least one follower when the at least one follower moves to
the end of the at least one cam slot .
The at least one guide groove may be formed to extend
in the direction of the optical axis.
Preferably, the end of the at least one cam slot is a
rear end of the at least one. cam slot, so that the at least
one follower contacts the surface when the first -barrel is
fully retracted into the second barrel.
Preferably, the second barrel is guided along the
optical axis without rotating about the optical axis
relative to a stationary block of the lens barrel.
Preferably, the third barrel is fitted on the second
barrel in such a manner that the third barrel is rotatable
about the. optical axis relative to the second barrel and
immovable along the optical axis relative to the second
barrel-.
.Preferably, the . at least one follower each includes a
follower projection formed on the outer periphery of the
first barrel, and a ring member supported on the follower
projection, wherein the follower projection and the ring
member engage with the at least one cam slot and the at
least one guide groove, respectively, and further wherein
the ring member contacts the surface when the follower
projection moves to the end of che cam slot.
Preferably, the follower projection and the at lea z
one cam slot, which engage with each other, are each tapered
in a direction away from the optical axis .
; Preferably, the at least one cam slot is oblique to the .
direction of the optical axis by a, predetermined angle.
Preferably, the at least one cam slot is provided at
the end thereof with an end slot which extends in a
circumferential direction of the second barrel, the at least
one member being formed along the end slot.
Preferably, the second barrel includes a first flange
formed substantially on a rear end of the outer periphery of
the second barrel so as to prevent the third barrel from
GB2 344662...
Page 30 of S3
7
moving forwardly from the second barrel along the optica!
axis, wherein the at least one is formed
with the first flange.
Preferably, the lens barrel further includes: a second
flange forced on a rearmost end of the outer periphery of
the second barrel behind - the first flange with a
circumferential groove formed therebetween; and at least one
Projection formed on a rear end of the third barrel and
extending inwardly toward the optical axis, the at least one
projection being positioned in the circumferential groove to
be guided along the circumferential groove so that the third
barrel is rotatable about the optical axis relative to the
second barrel while beinc restrinh^ «
ing restricted from moving along the
optical axis relative to the second barrel.
Preferably, the lens barrel further includes, a
stationary barrel in which the third barrel is positioned, a
male helicoid being formed on an inner periphery of the
stationary barrel; and a female helicoid formed on a rear
end of an outer periphery of the third barrel and engaging
with the male helicoid. so that the third barrel moves along
the optical axis when driven t n nr.*. ^
to r °tate about the optical .
axis relative tp the stationary barrel:
Preferably, the lens barrel, further includes: at least
one engaging projection formed on the second barrel and
extending outwardly in a radial ^ ^ ^
optical axis; and at least one linear guide groove formed on
the inner periphery of the stationary barrel, the at least
one engaging projection engaging with the at least one
linear guide groove so as to guide the second barrel along
the optical axis.
Preferably, the lens barrel further includes at least
one lead groove for the at least one the follower projection
to be inserted into the at least one cam slot during an
assembly of the lens barrel, the at least one lead groove
being formed on an inner periphery of a rear end of the
second barrel at a rear end of the at least one cam slot.
Preferably, a camera is- provided with the lens barrel/
the camera., including a .stationary •.. block, on. which .the
stationary barrel is integrally formed..
According to another aspect ; of the present invention,
there is provided a telescoping type of zoom lens having
first, second and third barrels concentrically arranged in
this order from, an optical axis. . . The telescoping type of
zoom lens includes: a plurality of cam slots formed on the
second barrel and extending parallel to one another oblique
to a direction of the optical axis; a plurality of guide
grooves formed on an inner periphery of the third barrel; a
plurality of followers formed on an outer periphery of the
first barrel and respectively engaging. with the plurality of
guide grooves through the plurality of cam slots; and a
Plurality of members each being integrally, formed on an
outer periphery of the second barrel adjacent to a rear end
of a corresponding one of the plurality of cam slots, the
Plurality of followers respectively contacting the plurality
of members when the first barrel is fully retracted ' into' the
second barrel.
According
to another aspect of the present invention, there is
provided a cam mechanism used for a photographic lens which
includes a moving barrel and a cam ring fitted on the moving
barrel such that the moving barrel is movable relative to
the cam ring along an optical axis of the photographic lens.
The cam mechanism includes: at least one cam slot formed on
the cam ring extending oblique to a direction of the optical
axis, wherein the at least one cam slot is formed such that
a cross-section along a plane perpendicular to a
longitudinal direction of the at least one cam slot tapers
in a direction away from the optical axis; at least one
follower projection integrally formed on the moving barrel,
wherein the at least one follower projection is formed to
taper in the direction away from the optical axis to be
firmly fitted in the at least one cam slot; at least one
lead groove for the. at least one follower projection to be
inserted into the at least one cam slot during an assembly
of the photographic lens, the at least one lead groove being
.formed on an inner periphery of a. rear end of the moving
barrel at a rear end of the at least one cam slot; at least
one follower respectively provided on the at least one
follower projection; and at least one stopper contacting the
at least one follower when the moving barrel is fully-
retracted into the cam ring : in . order to prevent ..the moving,
barrel from coming out of the .cam ring from a rear end
thereof, the at least one stopper being integrally formed on
an outer periphery of the moving barrel adjacent to the rear
end of the at least one cam slot.
Preferably, the photographic lens is a zoom lens.
Preferably, the cam ring is guided along the optical
axis without rotating about the optical axis relative to a
stationary block of the photographic lens.
Preferably, the at least one follower is a ring member
secured onto the at least- one follower projection by a
fixing screw . screwed in the at least one "follower
projection.
Preferably, the at least one cam slot is oblique to the
direction of the optical axis by a predetermined angle.
Preferably, the cam mechanism further includ.es: a
rotational barrel fitted on the cam ring to be rotatable
about the optical axis relative to the cam ring; and at
least one guide groove formed on an inner periphery of the
rotational barrel, the at least one follower being fitted in
11
the at least one guide groove to be guided therealong. '
The at least one guide groove may be formed to extend
• in the direction of the optical axis.
Preferably, the rotational barrel is fitted on the cam
ring to be immovable along the optical axis relative to the
cam ring.
According to yet another aspect of the present
invention, there is provided a cam mechanism used for a
Photographic lens which includes a moving barrel and a cam
ring fitted on the moving barrel such that the moving barrel
is movable relative to the cam ring along an optical axis of
the photographic lens. The cam mechanism includes: a
Plurality of cam slots formed on the. cam ring extending
parallel to one another oblique to a direction of the
optical axis, wherein the each of the plurality of cam slots
is formed such that, a cross-section along a plane
perpendicular to a longitudinal direction thereof tapers in
a direction away from the optical axis; a plurality of
follower projections integrally formed on the moving barrel,
wherein each of the plurality of follower projections is
formed to taper in the direction away from the optical axis
to be firmly fitted in a corresponding one of the plurality
of cam slots;, a plurality of lead grooves for each of the
Plurality of. follower projections to be inserted into a
corresponding one of the plurality of. cam slots during an
C L B . .2 344.662 .
Page 35 of 83
" . ' 12 \ . ' :
assembly of the photographic lens, each of the plurality of
lead grooves being formed'. on an Unner periphery' of a rear
end of the moving barrel at a rear end of a corresponding
one of the plurality of cam slots; a plurality of followers
each provided on a corresponding one of the plurality of
follower, projections; and a plurality of stoppers each
contacting a corresponding one of the plurality of followers
without contacting a corresponding one of the plurality of
follower projections when the moving barrel is fully
retracted into the cam ring in order to prevent the moving
barrel from coming out of the cam ring from a rear end
thereof, each of the plurality of stoppers being integrally
formed on an outer periphery of. the moving barrel adjacent
to a rear end of a corresponding one. of the plurality of cam
slots.
An example of the present invention will now
• . be described below in detail with
reference to the accompanying drawings in which similar
elements are indicated by similar reference numerals, and
wherein
Figure 1 is an exploded perspective view of a part of a
.zoom lens barrel ,-
Figure 2 is an enlarged perspective view of a linear
guide barrel of the zoom lens barrel shown in Figure 1;
GB 2 344 662
Paj5e.36.of 33
13
Figure 3 is an exploded sectional view of a part of the
zoom lens barrel;
Figure 4 is a sectional view of ; the /part of the: zoom
lens barrel shown in Figure 3 in an assembled state;
Figure 5 is a developed view of the outer periphery of
the linear guide barrel shown in Figure 2;
Figure 6 is an enlarged view of a part of the developed
view shown in Figure 5;
Figure 7 is an enlarged schematic perspective view
showing a part of the zoom lens barrel;
Figure 8 is a schematic perspective view showing the
part of the zoom lens barrel shown in Figure 7 in an engaged
state ,-
Figure 9 is an enlarged exploded perspective view of a
part of the zoom lens barrel ;
Figure 10 is a schematic perspective view illustrating
a state where an AF/AE shutter unit of the zoom lens barrel
is mounted to a first moving barrel;
. Figure 11 is an exploded perspective view illustrating
main parts of the AF/AE shutter unit of the zoom lens barrel
shown in Figure 7, 8, 9 or 10;
Figure 12 is an enlarged schematic perspective view of
the third moving barrel of the zoom lens barrel;
Figure 13 is a front elevational view of a fixed lens
barrel block of the zoom lens barrel;
Figure 14 is a sectional view of an upper. part of. the
zoom lens barrel, in a maximum extended state;
Figrure 15 is a sectional view of an upper part of the
zoom lens barrel, -illustrating main * ; .elements in a
housed stated-
Figure 16 is a sectional view, of the. upper part, of the
zoom lens barrel shown in Figure 15 in the maximum 1 extended
state;
Figure 17 is a sectional view of an upper part of the
zoom lens barrel in the housed state ;
Figure 18 is an exploded perspective view of the
overall structure of the. zoom lens barrel;.
Figure 19 is a block diagram of a controlling system
for controlling an operation of the zoom lens barrel;
Figure 20 is a sectional view of an upper part of a
lens supporting barrel . which supports a front lens group-
therein, and a lens fixing ring which is to be screw-engaged
with the lens supporting barrel;
Figure 21 is an enlarged perspective view of the lens
supporting barrel shown in Figure 20; and
Figure 22 is an enlarged sectional view of a . part of
the lens fixing ring shown in Figure 20.
Figure 19 is a schematic representation of various
15
elements which comprise a preferred embodiment of a zoom
lens camera to which the present invention is applied. A
concept of the present zoom lens camera will now be
described with reference to Figure 19.
The zoom lens camera is provided with a zoom lens
barrel (zoom lens) 10 of a three-stage delivery type
(telescoping type) having three moving barrels, namely a
first moving barrel 20, a second moving barrel 19 and a
third moving barrel (rotational barrel) 16, which are
concentrically arranged in this order from an optical axis
.0. in the zoom lens barrel 10 two lens groups are provided
as a photographic optical system, namely a front lens group
LI having positive power and a rear lens group . L2 having
negative power.
In the camera body, a whole optical unit driving motor '
controller 60, a rear lens group driving motor controller
61, a zoom- operating device 62, a focus operating device 63,
an object distance measuring apparatus 64, a photometering
apparatus 65, and an AE (i.e., automatic exposure) motor
controller 66, are provided. Although the specific focusing
system of the object distance measuring apparatus 64, which
is used to provide information regarding the object-to-
camera distance, does not form part of the present
invention, one such .suitable system is disclosed in commonly
assigned U.K. Patent Appl ication No . 2298331 ,. fUed on
Ga_2 344 662
fa_ge_39 of_83
16
February 22, 1996, and published on 28 August 1996,
Although the
focusing systems disclosed in U.K. Patent Application No.
2298331 are of the so-called "passive" type, other known
autofocus systems (e.g., active range finding systems .such
as those based on infrared light and' triangulation) . may be
used. Similarly,. a photometering system as disclosed in' the
above-noted U.K. Patent Application No. 2298331 could be
implemented as photometering apparatus 65 .
The zoom operating device 62 can be provided in the
form of, for example, a manually-operable zoom operating
lever (not shown) provided on the camera body or a pair of
zoom buttons, e.g., a "wide" zoom button and a "tele" zoom
button, (not shown) provided on the camera body. .When the
zoom operating device 62 is operated, the whole optical unit
driving motor controller 60 drives a whole optical unit
driving motor 25 to move the front lens group LI and the
rear lens group- L2, rearwardly or forwardly without regard
to a focal length and a focal point thereof:. In the
following explanation, forward and rearward movements of the
lens groups LI • and L2 by the whole optical unit driving
motor controller 60 (the motor 25) are referred to as. the
movement toward "tele"' and. the movement toward "wide"
respectively, since forward and rearward movements of the
lens groups LI and L2' occur when the zoom operating device
G8 2 344 662
_Page 40 of 83
17
62 is operated to "tele" and "wide- positions.
The image magnification of the visual field of a zoom
finder 67 provided in the camera body varies in sequence
with the variation of the focal length through the operation
of the zoom operating device 62. Therefore, the
photographer can perceive the variation Of the focal length
by observing the variation of image magnification of the
visual field of the finder. In addition, the focal length,
set by the operation of the zoom operating device 62, may be
perceived by a value indicated on an LCD (liquid crystal
display) panel (not shown) or the like.
When the -focus operating device 63 is operated, the
whole optical unit driving motor controller 60 drives the
whole optical unit. driving motor 25. At the same time the
rear lens group driving motor controller 61 drives a rear
lens group driving motor 30. Due to the driving of the
whole optical unit driving motor controller 60 and the rear
lens group driving motor controller 61, the front and rear
lens groups LI and L2 are moved to respective positions
corresponding to a set focal length and a detected object
distance and thereby the zoom lens is focused on the
subject.
Specifically, the focus operating device 63 is provided
with a release button (not shown) provided on an upper wall
of the camera body. A photometering switch and a release
switch (both hot. shown) are synchronized with the release
button. When the release button is half -depressed (half
step) ,. the focus operating device 63 causes the
photometering switch to be turned ON, and the object,
distance measuring and photometering commands are
respectively input to the object distance measuring
apparatus 64 and the -photometering apparatus 65..
When the release button is fully depressed (full step),
the focus operating device 63 causes the release switch to
be turned ON, and according to the result of object distance
measuring demand and a set focal length, the'whole optical
unit driving motor 25 and the rear lens group driving motor
30 are driven, and the focusing operation, in which the
front lens group LI and the rear lens group L2 move to the
focusing position, is executed. Further, an AE motor 29 of
an AF/AE (i.e., autof ocus/autoexposure) shutter unit
(electrical- unit) 21 (Figure 11) is driven via the AE motor
controller 66 to actuate a shutter 27. During the shutter
action, the AE motor controller 66 drives the AE motor 29 to
open shutter blades 27a of the .shutter 27 for a specified,
period of time according to the photometering information
output from the photometering apparatus 65.
When the zoom operating device 62 is operated, the zoom
operating device 62 drives, the whole . optical unit driving
motor 25 to move the front and rear lens groups LI and L2
§8.2.344 662
Page 42 of 83
.19'
together as a whole in the direction of the optical axis 0
(optical axis direction).. Simultaneous with such a
movement, the rear lens group driving motor 30 may also be
driven via the rear lens group driving motor controller 61
to move the rear lens group L2 relative to the first lens
group LI. However, this is not performed under, the
conventional concept of zooming in which the focal length is
varied sequentially without moving the position of the focal
point. When the zoom operating device 62 is operated, the
following two modes are available, namely:
1. a mode to move the front lens group LI and the rear
lens group L2 in the optical' axis .direction without varying
the distance therebetween by driving only the Whole optical
unit driving motor 25; and,
2. a mode to move the front lens group LI and the rear
lens group L2 in the optical axis direction while varying
the distance therebetween by driving both the whole optical
unit driving motor 25 and the rear lens group driving motor
30.
In mode 1, during a zooming operation an in-focus
condition cannot be obtained at all times with respect to a
subject located at a specific distance. However, this is
not a problem in a lens-shutter type camera, since the image
of the subject is not observed through the photographing
optical system, but through the. finder optical system that
is provided separate from the photographing optical system,
and It is sufficient to. only be focused when, the shutter is
released. In mode 2, during a zooming.. operation, the front
lens group LI and -the rear lens group L2- are moved without
regard to whether the focal point moves, and when the
shutter is released, the focusing operation (focus adjusting
operation) is carried out by moving both the whole optical
unit driving motor 25 and the rear lens group driving motor
30.
When the focus operating device '63 is operated in at
least one part of the focal length range set by the zoom
operating device 62, the whole optical unit driving motor 25
and the rear lens group driving motor .3 0 are driven to bring
the subject into focus. The amount of movement of each. lens,
group LI or L2 by the whole optical unit driving motor 2'5
and the rear lens- group driving motor 3 0 is- determined not
only using subject distance information provided from the
object distance measuring apparatus 64, but also by using
focal length information set by the zoom operating device
62. In such a manner, when the focus operating device 63 is
operated, by moving both the whole optical .unit driving
motor 2 5 and the rear lens group driving motor 30, the
position of the lens groups LI, L2 can be. flexibly
controlled, as compared with lens movements controlled by
• cam.
The zoom lens camera of this embodiment can also be
controlled in a different manner such that, during an
operation of the zoom operating device 62, only the
magnification of the zoom finder 67 and the focal length
information are varied without driving either the whole
optical unit driving motor 25 or the rear lens group driving
motor 30, When the focus operating device 63 is operated,
both the whole optical unit driving motor 25 and. the rear
lens group driving motor 30 are moved simultaneously
according to the focal length ' information and. the subject
distance information obtained by the object distance
measuring apparatus 64 to move the front lens group LI and
the rear lens group L2 to respective positions determined
according to the focal length and the subject distance
information.
An embodiment of the zoom lens barrel according to the
above -concept will now be described ..with reference to mainly
Figures 17 and. 18.
The overall structure of the zoom lens barrel 10 will
firstly be described.
The zoom lens barrel 10 is provided with the first
moving barrel 20, the second moving barrel 19, the third
moving barrel 16, and a fixed lens barrel block 12 . The '
third moving barrel 16 is engaged with a cylindrical portion
12p of the fixed lens, barrel block 12, and moves in the
optical axis direction upon being rotated. The third .moving
barrel 1.6 is provided on; an inner periphery thereof with, a
linear guide barrel (cam ring or second barrel) 17, which is
restricted in rotation. The linear guide barrel 17 and the
third moving barrel 16 move together as a whole in : the
optical axis direction, with, the third 'moving barrel .16
rotating relative to the linear guide barrel 17. The first
moving barrel 20 moves in the optical axis direction with
rotation thereof being restricted. The second moving barrel
19 moves in the optical axis direction, while rotating
.relative to the linear guide barrel 17 and the first moving
barrel 20. The whole optical unit driving motor 25. is
secured to the fixed lens barrel block 12. : ■ A . shutter
mounting stage 40 is secured to the first moving barrel 20.
The AE motor 2 9 and the rear lens group driving motor 30 are
mounted on the shutter mounting stage 40. The front lens
group LI and the rear, lens group L2 are respectively
supported by a lens supporting barrel (lens supporting
annular member) 34 and a lens supporting barrel 50.
An O-ring 70, made of a rubber or the like, is
positioned between an outer peripheral circumferential
surface of. the lens supporting barrel 34, in the vicinity of
the front end thereof, and an inner peripheral
circumferential surface of an inner, flange portion 20b
formed integral with the f irst \. moving barrel 20 in the
vicinity of the front end thereof, as shown in Figure 17.
The O-ring 70 prevents water from penetrating the zoom lens
barrel 1.0 at the front end thereof between the first moving
barrel 20 and the lens supporting barrel 34.
As shown in Figure 2 0, the front lens group LI consists
of five lenses, namely, a first lens (frontmost lens) Lla, a
second lens Lib, a third lens Lie, a fourth lens Lid and a
fifth lens Lie in this order from an object side to an image
side, i.e., from the left hand side to the right hand side
as viewed in Figure 20. .
A front positioning ring 36 for determining a distance
between the second lens Lib and the third lens Lie is
positioned and held between the second lens Lib and the
third lens Lie. An outer peripheral surface of the
positioning ring 36 is, fitted on an inner peripheral surface
of the lens supporting barrel 34. Likewise, a rear
positioning ring 37 for determining a distance between the
third lens Lie and the fourth lens Lid is positioned and
held between the third lens Lie and the fourth lens Lid. An
outer peripheral surface of the positioning ring 37 is
fitted on an inner peripheral surface of the lens supporting
barrel 34. The rear surface of the fourth lens Lid and the
front surface of the fifth lens Lie are cemented to each
other, so that the fourth and fifth lenses Lid, Lie are
formed as a cemented or composite lens. A front
circumferential -edge Llf of the second lens Lib along the
circumferential edge thereof contacts . the' rear surface^ of
the first lens Lla. A rear ■ circumferential edge LI g of the
fifth lens Lie. along the circumferential edge thereof
contacts an inwardly-projecting flange 34b formed integral
with the rear end of the lens supporting barrel 34.
A female thread 34a is formed on an inner periphery of
a front part of the lens supporting barrel 34, as shown in
Figure 20 or 21. A lens fixing ring 72, for fixing the
first lens Lla to the lens supporting barrel 34, engages
with the lens supporting barrel .34. With this arrangement, a
male thread 72a formed on the outer peripheral surface of
the lens fixing ring 7.2. meshes with the. female thread 34 a...
A circular abutting surface 72b- is formed on the lens fixing
ring 72 on an inner peripheral surface thereof. The
circular abutting surface 72b comes into contact with a
circumferential portion fp of the front surface of the first
lens Lla in a state when. the. lens fixing ring 72 is properly
screw-engaged • with the lens supporting barrel 34 . ' The
circular abutting surface 72b is formed to be substantially
parallel to the circumferential portion fp so that the
circular abutting surface 72b and the circumferential
portion fp may be brought tightly into contact with each
other when the lens fixing ring 72 is properly screw-engaged
with the lens supporting barrel 34.
G6 2.344 662.
Page. 48 of 83
25
A supporting ring portion 34c is formed integral with
the lens supporting barrel 34. The supporting ring portion
3 4c is located inwardly from the female thread 3 4a in a
radial direction of the lens supporting barrel 34 . The inner
peripheral surface: of the. supporting ring portion 34c, which
extends in the optical axis, direction, comes into contact ]
with an outer circumferential edge or surface op of the
first lens Lla. An annular positioning surface 34d,
extending substantially normal to the optical axis 0, is
formed on the lens supporting barrel 34 immediately behind
the supporting ring portion 34c. The circumferential edge
of the rear surface of the first lens Lla comes into contact
with the positioning surface 34d. With this .structure, . the
first lens Lla is immovably held between the circular
abutting surface 72b and the positioning surface 34d in the
optical axis direction, and the first lens Lla is immovably
held by the supporting ring portion 34 c in a radial
direction normal to the optical axis 0.
As shown in Figure 22, a coating 72e is coated on the
circular abutting surface 7.2 b. The coating 72e is a
waterproof coating made of a synthetic resin. m the
present ^embodiment, "Fantas Coat SF-6 (trademark of a
coating produced by the Japanese Company "Origin Denki
Kabushiki Kaisha") - is used. as the coating 72e. ' The front
surface of the first lens Lla is formed very smooth, whereas
26
the circular abutting surface -72b of the lens fixing ring 72
is not formed as smoothly (i.e., has a rough finish) as" the
front ■ surf ace- of the first ■ lens Lia . This is because the
first lens Lla is more minutely and accurately formed than
the lens fixing ring. 72 since the first lens' Lla is a
precision optical element. Due to this fact, were it not
for the coating 72e on the circular abutting surface 72b, a
substantial gap would be formed between the circular
abutting surface 72b and the circumferential portion fp even
if the circular abutting surface 72b properly and tightly in
contact with the circumferential portion fp by properly
screw-engaging the lens fixing ring 72 with the female
thread 34a. As a result, water or moisture would be able to-
penetrate into the lens supporting barrel 34 through the'
substantial gap. However, in the present embodiment, the
coating 72e is applied to the circular abutting surface 72b
so as to make the surface thereof a smooth surface which
does not cause to form such a substantial gap between the
circular, abutting surface 72b and the circumferential
portion fp when the circular abutting surface 72b properly
contacts the circumferential portion' fp. Accordingly, the
coating 72e, positioned and held between the circular
abutting surface 72b and the circumferential portion fp,
effectively prevents water or moisture from penetrating the
lens supporting barrel 3 4 between the circular abutting
surface 72b and the circumferential portion fp under the
condition that the circular abutting surface 72b is properly
and tightly in contact with the circumferential portion fp
by properly screw- engaging the lens fixing ring 72 with the
female thread 34a.
A circular surface 72c is formed on the. lens fixing
ring 72. The circular surface 72c is connected to the
circular abutting surface 72b and is located immediately
outward in a radial direction from the circular abutting
surface 72b. A front part of the outer circumferential
surface op of the first lens Lla (i.e., a circumferential
edge of the first lens Lla-) comes into contact with the
circular surface 72c when the lens fixing ring 72 properly
engages with the female thread 34a, Due to the circular
surface 72c contacting the. outer circumferential surface op,
the watertight structure between the circular abutting
surface 72b and the circumferential portion fp, that is
realized by the coating 72e, is enhanced. That is, a highly
efficient watertight connection ^between the first lens Lla
and the lens fixing ring 72 is realized by providing both
the coating 72e and the circular surface 72c with the lens
fixing ring 72 .
An annular recessed portion 34e is formed on the lens
supporting barrel 34 between the female thread 3 4a and the
supporting ring portion 34c. As shown in Figure 17, in a
GR2 344 662 .
Page 5 I_of 83
28
state where the lens fixing ring 72 is properly screw*
engaged with the female thread 34a, a rear end 72d -of' the
lens fixing ring 72 is positioned in- the annular recessed
portion 3 4e with the rear end 72-d /not contacting the bottom
(i.e., rearmost end) of the recessed portion 34e, namely, an
annular space is formed in the annular recessed portion 34e
between the rear end 72d and the bottom" of the recessed
portion 34e.
The fixed lens barrel block 12 is fixed in front of an
aperture plate 14 fixed to the camera body. The aperture
plate 14 is provided on a center thereof with a rectangular-
shaped aperture 14a which forms the limits of each frame
exposed. .The fixed, lens barrel block 12 is provided, on an
inner periphery of the cylindrical portion 12p, with a
female helicoid 12a, and also a plurality .of linear guide
grooves 12b each extending parallel to the optical axis 0,
i.e., extending in the ' optical axis direction. At the
bottom of one of the linear guide grooves 12b, namely 12b',
a code plate 13a, having a predetermined code pattern, is
fixed. The code plate 13a extends in the optical axis
direction and extends along substantially the whole of the
length of the fixed lens barrel block. 12. The' code plate
13a is part of a flexible printed circuit board 13
positioned outside the. fixed lens barrel block 12.
In the fixed lens barrel block 12, a gear housing 12c,
GR 2 344 662...
.Page 52 of-63
29
which is recessed outwardly from an inner periphery of the
cylindrical portion 12p'of the fixed. lens barrel block 12 in
a radial direction while extending in the optical axis
direction, is provided as shown in. Figure 13 or 18. In the
gear housing 12c, a driving pinion 15, extending in the
optical axis direction, is rotatably held. Both ends' of an
axial shaft 7 of the driving pinion 15 are rota.tively
supported by a supporting hollow 4, provided in the fixed
•lens barrel block 12, and a supporting hollow 31a, provided
on a gear supporting plate 31 fixed on the fixed lens barrel
block 12 by set screws (not shown), respectively. . Part of
the teeth of the driving pinion 15 project inwardly from' the
inner periphery of the ■ cylindrical portion 12p : " of the fixed
lens barrel block 12 so that the driving pinion 15 meshes
with an outer peripheral gear 16b of the third moving barrel
.16, as shown in Figure. 13.
On an inner periphery of the third moving barrel 16, a
plurality of linear .guide grooves 16c, each extending
parallel to the optical axis 0, are formed. At an outer
periphery of the rear end of the third moving barrel 16, a
male helicoid 16a and the aforementioned outer peripheral
gear 16b are provided as shown in Figure 12. The male
helicoid 16a engages with the female helicoid 12a of the
fixed lens barrel block 12. The outer peripheral gear 16b
engages with the driving pinion 15. The driving pinion 15
c L B -2 344-662
Page 53 of 83
has an axial length sufficient' to be capable of engaging
with -the outer peripheral gear 16b throughout the entire
range of movement of the third moving barrel 16 in the
optical axis direction.
As shown in Figure 2, the linear guide barrel 17 is
provided, on a rear part of an outer periphery thereof, with
a rear end flange 17d. The rear end- flange l7d has a
plurality of engaging projections 11c each projecting away
from the optical axis 0 in a radial direction.- The linear
guide barrel 17 is further provided, in: front of the rear
end flange 17d, with a retaining flange 17e. A
circumferential groove 17g is formed between the rear end
flange 17d and the retaining- flange 17e. . The retaining
flange 17e has a radius smaller than the rear end flange
17d. The' retaining 'flange 17e .is provided with a plurality
of cutout portions 17f. Each of the cutout portions 17f
allows a "corresponding engaging projection 16d to be
inserted into the circumferential groove 17g, as shown in
Figure 17 .
The third moving barrel 16 is provided, on an inner
«j . .. .
periphery of the rear end thereof, .with a plurality, of
engaging projections 16d. Each of the engaging projections
16d projects towards the optical- axis 0 in a radial
direction. By inserting the engaging projections 16d .into
the circumferential groove 17g, through the corresponding
GO, 2 344.662
. ..Page ..54 of 83
31
cutout portions 17f, the engaging projections 16d are
positioned in the circumferential groove 17g between the
flanges 17d and 17e (.see Figure 17). By' rotating the third
moving barrel 16 relative to the linear guide barrel 17, the
engaging projections 16d are engaged with the linear guide
barrel 17. .. • .
On the. rear end of the linear guide barrel 17, an
aperture plate 23 having a rectangular-shaped aperture 23a
approximately the same shape as the aperture 14a,. is fixed.
-. The relative rotation of the linear guide barrel 17,
with respect to the fixed lens barrel block 12, is
restricted by the .slidable engagement of the plurality of
engaging projections 17c with the corresponding- linear guide
grooves 12b, formed parallel to the optical axis 0.
A contacting terminal 9 is fixed to one of the engaging
projections 17c, namely 17c.-. The contacting terminal 9 is
in. slidable contact with the code plate 13a, fixed to the
bottom of the linear guide groove 12b', to generate signals
corresponding to focal length information during zooming.
On the inner periphery of the linear guide barrel 17 a
Plurality of linear guide grooves 17a. are formed, each
extending parallel to the optical axis 0. A plurality of
lead slots (cam slots) 17b are also formed on the linear
guide barrel 17 as shown, in Figure 2 or 18. The lead slots
17b are each formed oblique (inclined) to the optical axis
0. The linear guide barrel 17. may be provided, for example,
with three linear guide grooves 17a and three lead slots.
17b. More specifically, the *Lead slots 17b" extend parallel
to one another as shown in Figure 5 and each lead slot 17b
is oblique to both the optical axis direction (horizontal
direction as viewed in. Figure 5) and a circumferential
direction of the linear guide barrel. 17 (vertical direction
as viewed in Figure 5) by a predetermined angle.
Furthermore, each lead slot 17b is formed such that a cross-
section along a plane perpendicular to a longitudinal
direction thereof .tapers in a direction away from a
corresponding follower projection 19a, i.e., away from the
optical axis 0, to correspond- . to the shape of . the
corresponding follower projection. 19a.. .In other words, each
lead slot 17b is formed such 1 that side surfaces 17bs of each
lead slot 17b, with which the corresponding follower
projection 19a slidably contacts, approach each other in the
direction away from the corresponding, follower, projection
19a. A cross-sectional shape of each lead slot 17b along a
plane perpendicular to a longitudinal direction thereof is
accordingly trapezoidal corresponding to the shape of the
corresponding follower projection 19a, as can be seen in
Figure 3 or 4 .
The second moving barrel 19 engages with the inner
periphery of the linear guide barrel 17. On the inner
CiB„2 344662
Page_56_of 83
3 3 .
periphery of the second moving barrel 19;. a plurality of
lead grooves 19c are provided in a direction inclined
oppositely to the. lead slots 17b. Each lead groove' i9c is
oblique to both the optical axis direction and a
circumferential direction of .the linear guide barrel 17 by a
predetermined angle/ similar to each lead slot 17b. On the
outer periphery of the rear end of the second moving barrel
19 a plurality of follower projections 19a are provided.
Each of the follower projections 19a has a trapezoidal
cross-sectional shape projecting away from the optical axis : .
0 in a radial direction. The trapezoidal cross-sectional
shape corresponds to that of -the corresponding lead slot 17b
so that each follower projection 19a can firmly and slidably
contact the side surfaces 17bs of the corresponding lead,
slot 17b. The second moving barrel 19 is molded using a
synthetic resin, specifically, a polycarbonate-, containing 20
percent gl'ass fibers, arid the follower projections 19a are
integrally formed on the second moving barrel 19. The
second moving barrel 19 may be formed from other types- of
synthetic resins. The linear guide barrel 17 is also molded
using a polycarbonate containing 20 percent glass fibers,
but may be formed from other types of synthetic resins.
Follower pins 18 are positioned ih : . the .follower projections
19a. Each follower pin 18 consists : of a ring member 18a,
and a center fixing screw 18b which supports the ring member
GB 2 344 662.
Page 57 of 83
34.
18a on the corresponding follower projection 19a. The
follower projections 19a are in slidable engagement .with the
lead slots 17b of the linear" guide barrel 17, ' arid/ the
follower pins 18 are in slidable engagement with the linear
guide grooves 16c of the third moving barrel 16. With 'such
an arrangement, when the third moving barrel 16 rotates; the
second moving barrel 19 moves linearly in -the optical axis
direction, while rotating.
.On the. inner periphery of the second moving barrel 19,
the first moving barrel 20 is engaged. The first moving
barrel 20 is provided on an outer periphery of the rear
thereof with a plurality of follower pins 24 each engaging
with the corresponding inner lead groove 19c, and at the
same time the first moving barrel 20 is guided linearly by. a
linear guide member 22. The first moving barrel 20 is
provided at the front end thereof with a decorative plate 41
secured thereto.
As shown in Figures 7 and 8, the linear guide member 22
is provided with an annular member 22a, a pair of guide legs
22b and a plurality of engaging projections 28. The -pair of
guide legs 22b project f rom ' the annular member 2 2a in the
optical axis direction.. The plurality of engaging
projections 28 each project from the annular member 22a away
from the optical axis 0 in a radial direction. The engaging
projections 28 slidably engage with the linear guide grooves
17a. The guide legs 22b are respectively inserted into
linear guides 40c between the . inner peripheral surface of
the first moving barrel 20 and the AF/AE shutter unit 21.
The annular member 22a of the linear guide member 22 is
connected to the rear of the. second moving barrel 19 , such
that the linear guide member 22 and the second moving barrel
19 are capable of moving along the optical axis O as a
whole, and in addition are capable of relatively rotating
around the optical axis O. The linear guide member 22 is
further provided on the outer periphery of the rear end-
thereof with a rear end flange 22d. The linear guide member
22 is further provided in front of the rear end flange 2 2d
with a retaining flange- 22c. A circumferential .groove 22 f
is formed between the rear end flange 22d and the retaining
flange 22c. The retaining flange 22c has a radius smaller
than the rear end flange 22d. The retaining flange 22c is
provided with a plurality of cutout portions 22e, as shown
in Figure 7 or 8 , each allowing a corresponding engaging
projection 19b to be inserted into the circumferential
groove 22 f, as shown in Figure 17.
The second moving barrel 19 is provided on an inner ~
periphery of the rear end thereof, with a plurality of
engaging projections 19b, each projecting towards the
optical axis 0 in a radial direction. By inserting the
engaging projections 19b into the circumferential groove 22f
GB 2 344 662
Page .59 of S3
. . 36 •
through the corresponding cutout portions 22e, the engaging
projections 19b are positioned in the circumferential groove
22f between the flanges 22c and 22d. By rotating the second
moving barrel 19 relative to the linear guide member 22, the
engaging projections 19b are engaged with, the linear guide
member. 22 . With the above structure, when the second moving
barrel 19 rotates in the forward' or reverse rotational
direction/ the first moving barrel -20 moves linearly,
forwardly or rearwardly along the optical axis 0, but is
restricted from rotating.
At the front of the first moving barrel 20, a barrier
apparatus 3 5 having barrier blades 48a and 48b is mounted.
On an inner peripheral face of. the first- moving barrel 20
the AF/AE shutter uni t 21 having the .shutter 27 ,. consisting
of three shutter blades . 27a, is engaged and fixed, as shown
in. Figure 15, The AF/AE shutter unit 21 is provided. .with a
plurality of fixing holes 40a formed at even angular
intervals on the outer periphery of the shutter mounting
stage 40. Only one of the fixing holes 4.0a appears in each
of Figures 7 through 11 .
The aforementioned plurality of follower pins 24, which
engage with the inner lead grooves 19c, also serve as a
.device for fixing the AF/AE shutter, unit 21 to the first
moving barrel 20. The follower pins 24 are inserted* in
holes 20a, formed on the first moving barrel 20, and fixed
in the fixing holes 40a. With this arrangement the AF/AE
shutter unit 21 is secured to the first moving barrel 20 as
shown in Figure 10. In Figure 10 the first moving barrel 20
is indicated by phantom lines. The follower pins 24 may be
fixed by an adhesive, or the pins 24 may be formed as screws
to be screwed into the fixing holes 40a. ■
As illustrated. in Figures 11 and 18, the AF/AE shutter
unit 21 is provided with the shutter mounting stage 40, a
shutter blade supporting ring 46 fixed on the rear of the
shutter mounting stage 40 so as to be located inside the
shutter mounting stage 40, and the lens supporting barrel 50
supported in a state of being capable of movement relative •
to the shutter mounting stage 40. On the' shutter mounting
stage 40, the lens supporting barrel 34, the AE motor 29,
and the rear lens group driving motor 30, are supported.
The shutter mounting stage 40 is provided with an annular
member 40f having a circular aperture 40d. The shutter
mounting stage 40 is also provided with three legs 40b which
project rearward from the annular member 40f. Three slits
are defined between the three legs 40b. Two of the slits
comprise the aforementioned linear guides 40c, which
slidably. engage with the respective pair of guide legs . 22b
of the linear guide member 22 so as to guide the movement of
the linear guide member 22.
The shutter mounting stage 40 supports an AE gear train
38
45, which transmits- a rotation of the AE motor 29 to the
shutter 27, a lens driving gear train 42, which transmits
rotation of the rear lens group driving motor 30 to a screw
shaft 43, photointerrupters 56 and 57, connected to a
flexible printed circuit board 6, and rotating disks 58 and
59, having. a plurality of radially formed slits provided in
the circumferential direction. An encoder tor detecting 1
whether the rear lens group driving motor 30 is rotating and
for detecting an amount .of rotation of the rear lens group
driving motor 30 consists of the photointerrupter 57 and the
rotating disk 59. An AE motor encoder for detecting 'whether
the AE motor 29 is rotating and for . detecting an amount of
rotation of the AE motor 29 consists. of the photointerrupter
56 and the rotating disk 58.
The shutter 27, a supporting member 47 which pivotally
supports the three shutter blades. 27a of the shutter 27, and
a circular driving member 49, which gives rotative • power to
the shutter blades 27a, are positioned between the shutter
mounting stage 40 and the shutter blade' supporting ring 4.6, .:
secured to the shutter mounting stage 40. The circular
driving member 49 is provided with three operating
projections 49a at .even angular intervals, which
respectively engage with* each of the three shutter blades
27a. As shown in Figure:' 11, •. the shutter blade supporting
ring 46 is; provided at a front end thereof with a circular
GB 2 344 662
.Page 62 of 83
39
• aperture 46a and with three supporting holes 46b positioned
at even angular intervals around the circular aperture 46a.
Two deflection restricting surfaces 46c are formed on the
outer periphery of the shutter blade supporting ring 46.
Each deflection restricting surface 46c is exposed outwardly
from the corresponding linear guide 40c and slidably
supports the inner peripheral face of the corresponding
guide leg 22b.
The supporting member. 47, positioned in front of the
shutter blade supporting ring 46, is provided with a
circular aperture 47a, aligned with the circular aperture
46a of the shutter blade supporting ring 46., and with three
Pivotal shaf ts ,47b (only, one of which is illustrated in
Figure 11) at respective positions opposite the three
supporting holes 46b. Each shutter blade 27a is provided at
one end thereof with a hole 27b into which the corresponding
Pivotal shaft 47b is inserted, so that each shutter blade
27a is rotatable about the corresponding pivotal shaft 47b.
The major part of each shutter blade 27a, that extends
normal to the optical axis 0 from the pivoted end, is formed
as a light intercepts portion. All three light
interceptive portions of the shutter blades 27a together
prevent ambient light, which enters the front lens group LI,
from entering the circular apertures 46a and 47a when the
shutter blades 27a are closed. Each shutter blade 27a is
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Page_63_of 83
: 4-o ■-.
further provided, between, the hole 2.7.b and the light
intercept ive portion thereof, with a slot 27c, through which
the corresponding operating projection 49a is inserted. The
supporting member 47 is fixed to the shutter blade
supporting ring 4 6 in such a manner that each shaft 47b,
which supports the corresponding shutter blade 27a, is
engaged with the corresponding supporting hole 46b of the
shutter blade supporting ring 46.
A gear portion 49b is formed on a part of the outer
periphery of the circular driving' member 49. The- gear
portion 49b meshes with one of the plurality of gears in the
gear train 45 to receive the rotation from the gear train
45. The supporting member 4 7 is. provided, at respective,
positions close to the three pivotal shafts 47b, with three
arc grooves 47c each : arched, along a circumferential
direction. The three operating projections 49a of the
circular driving, ring 49 engage with the slots 27c of the
respective shutter blades 27a through the respective arc
grooves 47c. . The shutter blade supporting ring 46 is
inserted from the rear of the shutter mounting, stage 40, to
support the circular driving ring 49, the supporting, member
47 and the shutter 27, and is fixed on the shutter mounting
stage 40 by set screws 90 respectively inserted .through
holes 46x provided on the shutter blade ' supporting ring 46.
Behind the shutter blade, supporting ring 46, the lens
supporting barrel 50, supported to be able to move relative
to the shutter mounting stage 40 via guide shafts 51 and 52,
is positioned. The shutter mounting stage 40 and the lens-
supporting barrel 50 are biased in. opposite directions away,
from each other by a coil spring 3 fitted on the guide; shaft
51, and therefore play between the shutter mounting stage 40
and the lens supporting barrel 50 is reduced, m addition,
a driving gear 42a, provided as one of the gears in the gear
train 42, is. provided with a female thread hole (not shown)
at the axial center thereof and is restricted to move in the
axial direction. The screw shaft 43, one end of which is
fixed to the lens supporting barrel 50. engages with the
female thread hole. Accordingly, the driving gear
the screw shaft 43 together constitute a feed screw
mechanism. m such a manner,, when the driving gear 42a
rotates clockwise or anti-clockwise due to * • •
e cme to driving by the rear
lens group driving motor 30, the screw shaft 43 respectively
moves forwardly or rearwardly with respect to the driving
gear 42a, and therefore the lens supporting barrel 50, which
supports the rear lens group L2, moves relative to the front
lens group LI.
. A holding member 53 is fixed at t-y^ *
u ^ ea at tne front of the
shutter mounting staqe 40 Th* v^i^-
ge 4u. The holding member 53 holds the
motors 29 and 30 between rh^ Tn~i^-
^ecween the holding member 53 and the
shutter mounting staqe 4n Tho v^tj-
^ge .u. The holding member 53 has a
GS 2 344 662
.Page65 .pf_83
42
metal holding plate 5'5 fixed at the front thereof by set
screws 99. ' The motors 29 : , 30 and the photointerrupters 56,
57 are connected to. the flexible printed circuit board 6.
One end of the flexible printed circuit board . 6 is fixed to
the shutter mounting stage 40 .
After the first / second and third moving barrels 20, 19
and 16, and /the AF/AE shutter unit 21 and the like are
assembled, the aperture plate 23 is fixed to the rear of the
linear guide barrel 17, and an annular retaining member 33
is fixed at the front of the fixed lens barrel block 12.
In the zoom lens barrel 10 there is provided a
mechanism for preventing the zoom lens barrel 10 from being
damaged when a strong impact is applied to the front end. of
the zoom lens barrel 10 in a direction of retraction
thereof, while all the first through third moving barrels
.20, 19 and 16 are fully retracted in the fixed lens, barrel
block 12. Such a mechanism will be hereinafter discussed
with reference, to mainly Figures 1 through 6.
The mechanism for preventing the zoom lens barrel 10
from being damaged may be realized by the' third moving
barrel 16, the linear guide barrel 17 and the second moving
barrel 19.
.As shown in Figure 3 or 4, each of the plurality of
ring members 18a is provided with a circular recess 81b. A
head .-80a of the corresponding center fixing screw 18b is
seated on the circular recess 81b. A central hole 81a is
formed at. the center of ■ the bottom. of the circular recess
Sib, through which a threaded shaft 80b of the corresponding
center fixing screw 18b is inserted. A screw hole 19d is
formed on the second moving barrel 19 on each follower
projection. 19a. The thread shafts 80b are respectively '
secured to the screw holes 19d. The bottom edge of each
ring member 18a is tapered toward the second moving barrel
19 in a radial direction thereof, so that each ring member
18a is provided at a bottom edge thereof with a tapered
surface 81c. The linear guide barrel 17. -is provided, along
an. outer edge of each lead "slot 17b, with a tapered lead
surface 17n, which is . formed oblique by a predetermined
angle to firmly contact the .tapered surf ace 81c of the
corresponding ring member 18a. As can be seen from Figures
3, 4 and 6, a rearmost cuter edge of each lead slot 17b,
which extends along and is adjacent to the retaining flange
17e, is not formed as the tapered lead surface 17n.
The linear guide barrel 17 is provided, on the front
surface of the retaining flange 17e, with a plurality of
bumper surfaces 17m. Each of the bumper surfaces 17m is
positioned to correspond to the rear end of the
corresponding lead slot 17b. The ring members 18a
respectively bump against the bumper surfaces 17m when the
second moving barrel 19 is . driven to move back to its fully-
retracted position relative to the linear guide barrel 17,
that is, , when the zoom lens barrel 10 retracts to the
retracted position thereof. Each lead slot 17b is provided,
at a rear end thereof, with an end slot- 17b' (Figure 5)
which extends in .a . circumferential direction of the - linear
guide barrel 17 and extends along and is adjacent to the
retaining flange 17 e.
A lead groove 17.p* for the corresponding follower
projection 19a to be inserted into the corresponding lead
slot 17b during an assembly # of the zoom lens barrel 10, is
formed on an inner periphery of the rear end of the linear
guide barrel 17 at the rear end of each lead slot 17b.
During an assembly of the zoom lens barrel 10, when the
second moving barrel -19 is fitted iri the linear guide barrel'
17, firstly, the second moving barrel 19 is inserted into
the linear guide barrel 17. f;rom- the rear end thereof, .and
subsequently, the follower pro j ect ions 19a are respectively
inserted into the lead slots 17b through the lead gro.oves
17p. Thereafter, the ring members 18a are respectively
secured onto the follower projections 19a by the center
fixing screws 18b. Therefore, once the second moving barrel
19 and the linear guide barrel 17 are assembled in such a
manner, the second moving barrel. 19 cannot be- taken out of
the linear guide barrel 19 from the rear end thereof, since
the ring members 18a bump against the bumper surfaces 17m
when the second moving barrel 19 is moved back to its fully-
retracted position relative to the linear guide barrel. 17-.
Therefore, the bumper surfaces 17m function as stoppers to
prevent the second moving barrel 19 from coming out of the
linear guide barrel 17 from a rear end thereof.
The ring members 18a respectively and slidably fit. in
the linear guide grooves 16c as noted above, while the
follower projections 19a respectively and slidably fit in
the lead, slots 17b. Accordingly, when the third moving
barrel 17 moves along the optical axis 0 while rotating
about the optical axis 0 relative to the fixed lens barrel
block 12, the second moving barrel 19 moves along the
optical axis 0 : relative to the third moving barrel 16 while
rotating together with the third . moving barrel .16 in the
same rotational direction relative to the fixed lens barrel
block 12, .
The lead, slots 17b are formed as linear grooves, each
of which is oblique to both the optical axis direction and a
circumferential direction of the linear guide barrel 17 by a
predetermined angle as noted above, so that the follower
pins 18 are driven to move in the optical axis direction at
a cons tant speed when the third moving . barrel 16 is driven
to rotate at ;a constant . rotational speed. However, each
lead slot 17b is regarded as a particular type of cam slot
for moving the corresponding follower pin 18 in the optical
axis direction' at .a: speed having no variation when the third
moving barrel" 16 is driven to rotate at a" constant
rotational speed. Therefore, the lead slots 17b may be
considered . to be cam slots formed. on the linear guide barrel
17,
Generally, when an impact' is applied to the front end
of a telescoping- type of zoom •lens'- in .'a direction' of
retraction thereof while the zoom lens is advanced from a
camera body/ the impact will be absorbed by a clutch,
helicoids, cam slots, cam grooves or the like, provided. in
the zoom lens, without the occurrence of any damage, in the
case where the lead of the helicoids, cam slots, cam grooves
or the like is small. An arrow "A" . show, in Figure 6
represents a direction of such an impact. However, when a . ■
strong impact is applied to the front end of the telescoping
type of zoom lens barrel in' a direction of retraction
thereof while the zoom lens barrel is fully retracted, the
helicoids, cam slots, cam grooves and/or peripheral, members
in the zoom lens may be damaged, particularly in the case
where the lead of the helicoids, cam slots, cam grooves' or
the like is large. However, the zoom lens barrel 10 of the
present embodiment does not easily suffer from such a
problem. In the zoom lens barrel 10, in the case when an
o
impact is applied to the front end of the zoom. lens barrel
1.0 in a direction of retraction thereof while all the first
through third moving barrels 20, 19 and 16 are being fully
retracted into the fixed lens barrel block' 12, i.e., with
the follower pins 18 being respectively located at the end
slots 17b' of the lead slots 17b as shown in Figure 6, the
impact is received not only by the end slots 17b • of the
lead slots 17b through the follower projections 19a but also
by the retaining flange 17 e at the bumper surfaces 17m
through the ring members 18a,
An arrow »B» shown in Figure 6 represents a direction
of the impact applied to the retaining flange 17e through
one of the ring members 18a. If the impact, were received by
merely the rear ends of the lead slots 17b through the
follower projections 19a, the rear ends of the lead slots
17b would be damaged and/or. the follower pins 18 and the
follower projections 19a would run-off the lead, slots 17b,
which may cause damage to the zoom lens barrel 10. However,
since the 'impact is received by not only the end slots 17b'
through the follower projections 19a but also the retaining
flange 17e, whose strength 'is sufficiently strong, through
the ring members 18a, the zoom lens barrel is less likely
to be damaged. *
In the zoom lens barrel 10 there is provided a cam :
mechanism for producing a predetermined movement between two
moving barrels (the second and third barrels 16, 19) which
are concentrically arranged. The cam mechanism includes the
GE.2 344 662
Page .7.1 of_83
48
linear guide barrel 17,, the follower projections 19a of the
second moving barrel .19, the follower, pins 18, the linear,
guide grooves 16c of the third moving barrel 16, etc..
The linear guide barrel 17 and the second moving barrel
19 are assembled in the following manner. Firstly, the
second moving barrel 19 is inserted into the linear guide
barrel 17 from the rear end thereof while each of the
follower projections 19a is inserted into a corresponding
one of the lead grooves 17p. Thereafter, each of the ring
members 18a is placed on the top of a corresponding one of
the follower projections 19a, which comes out of the
corresponding lead slot 17b, and subsequently, each ring
member 18a is secured to the corresponding follower
projection 19a by screwing the fixing screw 18 in the screw
hole 19d. In this state, the second moving barrel 19 cannot
be taken out of the linear guide barrel 17 from the rear end
thereof since the ring members 18a respectively contact the
bumper surfaces 17m when the second moving barrel is in a
state of being most retracted relative to the linear .guide
barrel 17.
In the case where each of the lead slots 17b is formed
merely as a conventional lead slot, that is, a lead slot
whose side surfaces extend parallel to each other and thus
do not approach each, other in a direction away from the
corresponding follower projection 19a and also the case
Gft2 .344 662.
Page 72 of 83
49
where each of the-/ followers, which engage with a
corresponding one of such conventional lead slots and a
corresponding, one of the linear guide grooves 16c, is formed
merely as a single follower integrally formed on the second
moving barrel 19, not as a combination of the follower
projection 19a and the ring member 18a, a mold used for
molding the linear guide barrel 17 would have quite a
complicated structure which may be comprised of a plurality
of mold pieces. In addition, in the case where the
aforementioned single follower is integrally ' formed on the
second moving barrel 19, instead of the combination of the
follower projection 19a and-the ring member 13a, each lead
groove 17p needs to be provided as, a lead slot which
penetrates completely through the linear guide barrel 17 in
a radial direction thereof, because each single follower
will be much longer than the . thickness of the linear guide
barrel 17 in the radial direction. This deteriorates the
strength of the linear guide barrel at a rear portion
thereof. In this case, if such a strength needs to be
maintained, the linear guide barrel 10 must be formed
thicker at the rear portion thereof, which results in
increasing the size of the zoom lens barrel 10.
However, according to the zoom lens barrel 10 of the
present embodiment, such a problem is overcome due to the
aforementioned structure in which the ring members 18a are
respectively fixed to the follower- projection 19a after the
second moving barrel" 19 has"- been, ihserted;, in the ; linear
guide barrel 17 during assembly, Jh addition, since the
ring members. 18 a and the follower projections 19a are
separately formed and since each follower projection 19a is
tapered in a direction away from the optical axis. 0, a mold
to be used for molding the linear guide barrel 17 can be
formed as a mold having a simple structure.
In the above-described embodiment of the ' zoom lens
barrel 10, although the zoom lens optical . system consists of
two movable lens groups, namely the front lens group LI and
the rear lens group L2 , it should be understood that the
present invention is not limited . to; 'the present embodiment
disclosed above, but the present, invention, may also be .
applied to another type of zoom lens optical ' system
including one or more . fixed lens group,.
In addition, in the above embodiment, the rear lens
group. LI is provided as a. component of the AF/AE shutter
unit 21, and .the AE motor 29 and the." rear lens group driving
motor 30 are mounted to the AF/AE shutter unit 21, With,
such a structure, the structure for supporting the front and
rear lens groups LI and L2 and the structure for driving the
rear lens group L2 are both simplified. Instead, of adopting
such a structure, the zoom lens barrel 10 may also be
realized in such a manner by making the rear lens group L2 a
member separate from the AF/AE shutter unit 21, which is
provided with the shutter mounting stage 40, the circular,
driving member 49, the supporting member 47, the shutter
blades 27, the shutter blade supporting ring 46 and the
like, and that the rear lens group L2 is supported by any
supporting member other tha°n the AF/AE shutter unit" 21.
In the zoom lens camera of the present embodiment, the
operation by rotation of the whole optical unit driving
motor 25 and the rear lens group driving motor 30 will now
be described with reference to Figures 14, 15, 16 and 17.
As shown in Figure 15 or 17, when the zoom lens barrel
10 is at the most retracted -(withdrawn) position, i.e., the
lens-housed condition, when the power switch is turned ON,
the whole optical unit driving motor 25 is driven to rotate
its drive shaft in the forward rotational direction by a
small amount. This rotation of the motor 25 is transmitted
to the driving pinion 15 through a gear train 26, which is
supported by a supporting member 32 formed integral with the
fixed lens barrel block 12, to thereby rotate the third
moving barrel 16 in one predetermined rotational direction
to advance forwardly along the optical axis 0. Therefore,
the second moving barrel 19 and the first moving barrel 20
are each advanced by a small amount in the optical axis
direction, along with the third moving barrel 16.
Consequently, the camera is in a state capable of
photographing, with the zoom lens positioned at the widest,
position, i'.e. # the wide. .end. At this stage,- due to the
fact that the amount of movement of the linear guide barrel
17, with respect to the fixed lens barrel block 12, is
detected through the relative slide between the code plate
13a and the contacting terminal 9, the focal, length of the
zoom lens barrel 10, i.e., the front and rear lens groups LI '
and L2, is detected.
In the photographable state as above described, when
the aforementioned zoom operating lever is manually ' moved
towards a "tele" side, or the "tele" zoom button is manually
depressed to be turned ON, the whole optical unit driving
motor 25 is driven to rotate its drive shaft in- the •forward-
rotational direction through the whole optical .unit-, driving
motor controller 60 so that the third moving barrel 16"
rotates in .the rotational direction to advance along the
optical axis O via the driving pinion 15 and the outer
peripheral gear 16b. Therefore, the third moving barrel 16
is advanced from the fixed lens barrel block 12 according to
the relationship between the female helicoid 12a and the
male helicoid 16a. At. the same time, the linear guide
barrel 17 moves forwardly in the optical axis direction
together with the third moving barrel 16, without relative
rotation to the fixed lens barrel block 12, according to the
relationship between the engaging pro lections 17c and the
53
linear guide grooves 12b. At this time, the simultaneous
engagement of the follower pins 18 with the respective lead
slots 17b and linear guide grooves 16c causes the second
moving barrel 19 to move forwardly relative to the third
moving barrel 16 in the optical axis direction., while
rotating together with the third moving barrel 16 in the
same rotational direction relative to the fixed lens barrel
block 12. The first moving barrel 20 moves forwardly from
the second moving barrel 19 in the optical axis direction,
together with the AF/AE shutter unit 21, without relative
rotation to the fixed lens barrel block 12, due to the
above-noted structures in which the first moving barrel 2 0
is guided linearly by the linear guide member 22 and in
which the follower pins 24 are guided by the lead grooves
19c. During such movements, according to the; fact that the
moving position of the linear guide barrel 17 with respect
to the fixed lens barrel block 12 is detected through the
relative slide between the code plate 13a and the contacting
terminal 9, the focal length set by the zoom operation
device 62 is detected.
Conversely, when the zoom operating lever is manually
moved, towards a "wide" side, or the "wide" zoom button is
manually depressed to be turned ON, the whole optical unit
driving motor 25 is driven to rotate its drive shaft in the
reverse rotational direction through the whole optical unit
driving motor controller 60. so that the third moving barrel
16 rotates in the rotational direction to retract into the
fixed lens barrel block 12 together with the linear guide
barrel 17. At the same time, the second moving barrel 19 is
retracted into the third movin g : barrel 16 , while rotating in
the same direction as that of the ' third moving barrel 16,
and the first moving barrel 20 is' retracted into the
rotating second moving barrel 19 together with the AF/AE
shutter unit 21. During the above retraction driving, like
the case of advancing driving as above described, the rear
lens group driving motor 30 is not driven.
While the zoom lens barrel 10 is driven during the
zooming operation, since the rear lens group driving motor
30 is not driven, the front lens group LI and the rear lens
group L2 move as a. whole, maintaining a constant distance
between each other, as shown in Figure 14 or 1.6. The .focal
length input via the zoom code plate 13a and the contacting
terminal 9 is indicated, on an LCD panel (not shown) provided
on the camera body .
At any focal length set by the zoom operating device
62, when the release button is depressed by a half-step, the
object distance measuring apparatus 64 is actuated to
•measure a current subject distance. At the same time the
photometering apparatus 65 is actuated to measure a current
subject brightness. Thereafter, when the release button is
fully depressed, the whole optical unit driving motor 25 and
■ the rear lens group' driving motor 30 are each driven by
respective amounts dictated according to the focal length
information set in advance and the subject distance
information obtained from the object distance measuring
apparatus 64 so that the front and rear lens groups LI and
L2 are respectively moved to specified positions to obtain a
specified focal length to thereby bring the subject into
focus. immediately after the subject is brought into focus,
via the AS motor controller 66, the AZ motor 29 is driven to
rotate the circular driving member 49 by an amount
corresponding to the subject -brightness information obtained
from the photometering apparatus 65 so that the shutter 27
is driven to open the shutter blades 27a by a specified
amount which satisfies the required exposure. Immediately
after such a shutter release operation, in which the three
shutter blades 27a are opened and subsequently closed, is
completed, the whole optical unit driving motor 25 and the
rear lens group driving motor 30 are both driven to move the
front lens group LI and the rear lens group, L2 to the
respective initial positions at which they were at prior to
a shutter release.
in the present embodiment of the zoom lens barrel 10/
"Fantas Coat SF-6" is used as the coating 72e. However, a
different type of coating may be used as the coating 72e as
£8.2 344 662
Page 79 of 83
56
long as it is waterproof and makes the circular abutting
surface 72b a smooth surface to form substantially no gap
between the circular abutting surface 72b and the
circumferential portion fp.
Obvious changes may be ' made, in the- specific embodiments .:
of the. present invention described herein, such:
modifications being within the . scope of the
invention claimed. It is indicated that all matter
contained herein is illustrative and does not limit the
scope of the present invention .
'57
CLAIMS : -
1. A cam mechanism used for a photographic lens which
includes a movable barrel and a cam ring fitted on said movable
barrel such that said moving barrel is movable relative to said
cam ring along an optical axis of said photographic lens, said
cam mechanism comprising:
at least one cam slot formed on said cam ring extending
obliquely to a direction of . said optical axis, wherein said at
least one cam slot is formed such that a cross-section along a
plane perpendicular to a longitudinal direction of said at
least one cam slot tapers in a direction away from said optical
axis;
at least one follower projection integrally . formed on said-
movable barrel, wherein said at least one follower pro jection :
is formed to taper in said direction away from said optical,
axis to be firmly fittable in said at least -one cam slot;
at least one lead groove for allowing insertion of said at
least one follower projection into said at least one cam slot
during an assembly of said photographic lens, said. at least one
lead groove being formed on an inner periphery of a rear end of
said moving barrel at a rear end of said at least one cam slot;
at least one follower respectively provided on said at
least one follower projection;* and
at ' least one stopper for contacting said at least one
' . 58 '
follower when said moving barrel is fully retracted into said
cam ring for preventing said movable barrel from' coming out of
said cam ring from a rear, end- thereof, said at least one
stopper being integrally formed on an outer, periphery ■ of said
movable barrel adjacent to said rear- end of said at least one
cam slot .
2. A cam mechanism according to claim 1/ wherein' said
photographic lens is a zoom lens.
3. A cam mechanism according to claim 1 or 2, wherein said
cam ring is guidable along said optical axis without rotating
about said optical axis relative to a stationary block of. said
photographic lens..
4. A cam mechanism according to', any. one of claims 1, 2 or
3, wherein said' at least one •follower' is a ring member
securable onto said at least one follower projection by a
fixing screw screwable in said ' at least one follower
projection.
5. A cam mechanism according to any one of claims 1 to 4,
wherein said at least one cam slot is oblique to said direction
of said. optical axis by a predetermined angle,
6. A cam mechanism according to any. one of claims' I -to 5,
further comprising:
a rotational barrel fitted on said cam ring to be
rotatable about said optical axis relative to said cam ring;
Page 82 pf 83
' 5-9
and
at least one guide groove formed on. an' inner periphery of
said rotational barrel, said at least one follower being fitted
in said at least one guide groove to be guidable therealong.
7. A cam mechanism according to claim 6,' wherein said at
least one guide groove : extends in said direction of said
optical axis.
8. A cam mechanism according to claim 6 or 7, wherein said
rotational barrel is fittable on said cam ring to be immovable
along said optical axis relative to said cam ring.
9. A cam mechanism substantially as hereinbefore described
with reference to Figures 3 to 6. of the accompanying ' drawings .
% Office I
INVESTOR DC PEOPLE
Application No:
Claims searched:
GB 0005104.5
1-9
Examiner:
Date of search:
Chris Ross
4 April 2000
Patents Act 1977
Search Report under Section 17
Databases searched:
UK Patent Office collections, including GB, EP, WO & US patent specifications, in:
UK CI (Ed. R): G2J(J23C)
IntCl (Ed. 7): G02B
Other:
Documents considered to be relevant:
Category
Identity of document and relevant passage
Relevant
to claims
A
ft
GB 2237406 A (ASAHI) parts 10c, 19a, 20b, E
US 4707083 A (CANON) the Figs .
Document indicating lack of novelty or inventive step
Document indicating lack of inventive step if combined with
one or more other documents of same category.
Member of the same patent family
Document indicating technological background and/or state of the an.
Document published on or after the declared priority date but before the
fHmg date of this invention.
Patent document published on or after, but with priority date earlier than,
the filing date of this application.
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